Inspired by the Showa era goldfish vending stalls. These were most often set up along the approaches to local shrines and temples with dozens of other specialty stalls that enlivened summer festivals in Japan (and still do). Back then, the glass globes (miniature goldfish bowls) hung from bamboo slats under the eaves of the stall-- a prop to make customers feel cooler in the sultry evenings of high summer, I think.
Other goldfish are sold from tanks set on the ground, and children pay for a chance to scoop them up with plastic-framed paper scoops that usually get soggy and tear before they can catch any fish. So they pay for another scoop. And another. As long as the coins that are clutched in their sweaty little palms last.